Modeling the Fluid Flow around Airfoils Using Conformal Mapping

Abstract

The modeling of fluid interactions around airfoils is difficult given the complicated, often non-symmetric geometries involved. The complex variable technique of conformal mapping is a useful intermediate step that allows for complicated airfoil flow problems to be solved as problems with simpler geometry. In this paper, we use the conformal mapping technique to model the fluid flow around the NACA 0012, 2215, and 4412 airfoils by using the Joukowsky transformation to link the flow solution for a cylinder to that of an airfoil. The flow around a cylinder was derived with the superposition of elementary potential flows using an inviscid, incompressible fluid model. Lift calculations as a function of angle of attack for each airfoil were obtained using the transformed flow solutions and fundamental theories of aerodynamics. These calculations are compared against lift calculations provided by the thin airfoil method. Lift calculations for the NACA 0012 airfoil match well with expected results, while there is a discrepancy at low angles of attack for the 2215 and 4412 airfoils. Key Terms: NACA airfoil, conformal mapping, Joukowsky transformation, inviscid flow.